Features

No. 25 - Halogenated Flame Retardants

The use of flame-retardant additives predates 1955, but applications were largely limited in those days to PVC, polyurethanes, and textiles.

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The use of flame-retardant additives predates 1955, but applications were largely limited in those days to PVC, polyurethanes, and textiles. Geigy in Switzerland (later Ciba-Geigy) offered coal-tar based phenolic phosphates in the early ’50s. Synthetic phosphate esters were developed in the late 1960s by Ciba-Geigy under the Reofos trade name. (Reofos is now owned by Chemtura.)

In the 1960s, liquid chlorinated paraffins had wide usage in the dual function of plasticizer and flame retardant in PVC and elastomers. Chlorinated and brominated phosphate esters also emerged from companies such as Stauffer Chemical and FMC for rigid and flexible PUR foams.

Hooker Chemicals (acquired by Occidental Chemical) was among the first suppliers to develop flame retardants specifically for non-plasticized thermoplastics. It launched a solid chlorinated cycloaliphatic called Dechlorane in about 1962. It was aimed at PP, PE, HIPS, and ABS. That was followed in 1964 with Dechlorane Plus, which had improved heat stability and less blooming tendencies. The first commercial applications for Dechlorane Plus included PP electrical parts for televisions and nylon electronic components. It is still used today in nylon and polyolefin wire and cable.

The growth of flammability standards and regulations during the 1970s on products like television cabinets, wire/cable coatings, auto interior furnishings, electrical parts, and building materials led to major increases in FR usage in plastics. In the 1970s, Dow Chemical, Great Lakes, Velsicol (later Michigan Chemical and then Great Lakes), Cities Service, Chemetron, and American Cyanamid pioneered in brominated flame retardants. They were joined in the 1980s by Ethyl Corp. (now Albemarle) and Dead Sea Bromine (Ameribrom).

In the early 1970s, tetrabromobisphenol A (TBBPA) was the first brominated FR to see large-scale usage, and to this day its main use has been in epoxy for applications such as circuit boards.

Decabromodiphenyl oxide (DBDPO), introduced by Dow in the very early ’70s, was the second widely used brominated FR. It was aimed at HIPS TV cabinets and ABS housings for desktop calculators, printers, and computer monitors.

In the 1980s, FR-PP got a big push from the popularity of PP Christmas-tree lights from Japan, which had to meet a UL 94V-2 standard. This revived interest in a TBBPA derivative (Great Lakes’ PE-68), which had been around since the ’70s.

Nowadays there is a trend that originated in Europe toward replacing halogenated flame retardants. But over the years, these products have significantly reduced the risk of fires. For example, fires originating in TVs are almost non-existent in the U.S., while in Europe, which only recently adopted comparable TV flammability standards, the incidence of TV fires has been over 100 times as great. A study in the U.K. found that the number of deaths from furniture fires was reduced by over 3000 per year when FR furniture was required in 1988.